Balloon for tandem flight and method of flying meteorological balloons



D. c. JALBERT 2,475,839

BALLOON FOR TANDEM FLIGHT AND METHOD OF FLYING METEOROLOGICAL BALLOONS Filed July 30, 1948 July 12, 1949.

. INVENTOR.

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Patented July 12,949

UNITED STATES TENT OFFICE BALLOON FOB TANDEM FLIGHT AND METHOD OF FLYING METEOROLOGI- CAL BALLOONS setts Application July 30, 1948, Serial No. 41,638

4 Claims.

This invention relates to meteorological ba1 loons, particularly to a method of flying ballons which allows substantial weights to be raised to extreme heights.

Meteorological balloons are commonly expansible envelopes made as thin and as light as po sible in order to reduce the non-paying load. As these balloons penetrate higher and higher atmospheric levels, they expand, thinning the en- Eventually, the balloons break and the radiosondes or other exploration instruments are parachuted to earth.

Although every eflort is made to reduce the weight of apparatus which must be carried aloft, there are numerous situations in which the weightalifting capacity of single meteorological balloons is .exceeded so that two or more balloons must be used to carry the load. When this is necessary, two types of flight have been commonly used: (a) The cord tied to the neck of the balloon and suspending the instruments has been branched so that the balloons are tied at the open arms of a Y or a more complex branched rigging; (b) the follower balloons have been tied on the .cord at some distance below the lead balloon. In the first instance, the envelopes of the balloons are pulled into contact with each other. In the second instance, the envelope of the follower balloon is pulled into contact with the suspending cord. Bumping of the envelopes or contact with the cord may cause a premature failure because, for example, a 1400 gram balloon has a flaccid diameter of 67 inches and its envelope is .004" thick at sea level. At maximum elevation, about 80,000 feet, its diameter is 31 feet, and the thickness of the envelope has been reduced to 0.00013 inch. It is easily seen that films as thin as this may break on contact with other films and particularly if they are bumped against the cord which supports the recording instrument.

The object of my invention is to prevent premature bursting in tandem or multiple balloon flights. My improved method of flying meteorological balloons keeps the balloons exactly in line with the cord and prevents their envelopes from coming into contact either with each other or with the suspending cord. In consequence, it provides a dependable Weight-carrying rigging which allows the balloons to reach higher levels while carrying heavier loads than has previously been practical.

I have discovered that a pierced rubber plug can be slid along a smooth cord, for example, a nylon 65- lb. cord, with remarkably little frictional resistance and that, surprisingly, the gas atmosphere retained behind the plug will not leak out along the pierced passageway between the rubber and the cord to any significant degree. Accordingly, my invention contemplates passing the cord which suspends the recording instrument through a rubber plug which occupies the north pole of the follower balloon, passing the cord completely through the follower balloon, and bringing it out through the normal inflation opening in the neck of the balloon. In flight, the plug slides up the cord as the balloon envelope expands.

In the drawings,

uigure it is a diagrammatic representation of the balloons in flight. The dotted lines show the envelopes after high levels have been reached the envelopes have expanded. The representation is not drawn to scale.

,Figure 2 is a detail vertical section through the plug portion and the neck portion of a balloon equipped for tandem flight according to my invention.

Referring to the drawings, the lead balloon it! is a standard meteorological balloon and is equipped. as is usual, with a bridle H lashed around its neck l2. Cord l3, which should be 5 to 10 feet longer than the maximum expanded diameter of the balloon and to which the parachute as and the recording instrument l5 are attached, passes through the follower balloon l6. At the north pole of the balloon I6, I attach a domed rubber plug I? (Figure 2). The plug has a cylindrical portion l8 and a flange section [9. The plug is conveniently attached by punching a small hole in the envelope 20, inserting the plug and cementing its flange 19 to the envelope 20 and seizing the plug and envelope together by the seizing H which surrounds the cylindrical portion it of the plug. The cord is led out through the tapered inflation opening 22 of the rubber necl -plug ll (parts I I, ll, 22 and 24 are conventional meteorological balloon construction), and is passed through and then tied to a small wooden dowel which acts as a stop stick 23. After the balloons are inflated, the rubber stopper 2 is inserted in the tapered opening 22. The stop stick 23 contacts with the end of the rubber stopper 24. Merely for clarity of illustration, it is shown somewhat spaced from the stopper in Figure 1.

The advantages of my improved method will be apparent from the following. Assume that an ascension velocity of approximately 400 feet per minute is desired and that the weight of the instruments to be carried aloft is 6800 grams and that the largest balloon available at the Weather Station is a standard 2,000 gram balloon. For flight, of a single balloon, the balloon would be inflated, at sea level, with 306' cu. ft. of gas to a diameter of 8.36 feet. The gross lift of the balloon is then 9200 grams. The expansibility ratio (from sea level to maximum elevation) is 123.84. The balloon will burst at approximately 88,000 feet.

If, now, we use two balloons and wish an ascension velocity of 400 feet per minute and want to reach 100,000 feet elevation, each balloon will carry 7 /2 pounds. The balloons will be inflated with 188 cu. ft. of gas to a diameter of 7.11 feet at sea level. Since the expansibility ratio before bursting is now 1:45 because of the lowered sea level diameter, it may be expected that the balloons will rise to 102,000 feet. For convenience, I have followed the usual practice for meteorological balloon calculations and have assumed an ideal gas, the characteristics of which lie exactly halfway between hydrogen and helium. Calculations on the "ideal gas basis are sufiiciently accurate for most observations.

It would be expected that a. considerable amount of such light and mobile gases as hydrogen or helium would be lost through the aperture pierced in the plug and that the gas would travel outwardly along the fibers of cord l3. Surprisingly, this does not take place. moves easily along the string, effectively seals the passageway between the string and the plug. Combined diffusion and leakage tests conducted over 67 hours gave the following results, which show that all significant loss of gas is due to diffusion through the envelope:

The plug imposses no measurable back pressure upon inflation. Normal and plug balloons have been inflated and inflation pressures measured on an alcohol manometer. No significant differences were noted.

The above discussion shows the advantage of using two balloons or any number of balloons when the weight to be supported exceeds the carrying capacity of the balloon for the height of the ascent which it is desired to reach.

The method of flying does not necessarily require a plug. In an emergency, a hole may be pierced in a standard balloon, the suspension cord passed through the hole, and the envelope may The plug, although it 4 be bunched about the cord and secured with a thread lashing. The balloon will slide up the cord, but unless the folds are carefully made, leakage through folds may prove excessive.

My new method of tandem flying has been tested by the official agencies, and it has been found that the expected heights are reached and premature bursting by the bumping of the envelopes or contact with the suspending cord is avoided.

I claim:

1. A meteorological balloon having an expansible envelope and a neck, a thickened portion on the envelope provided with an aperture located diametrically opposite the neck, a suspension cord passing through the aperture and extending outwardly of the balloon through said aperture and through said neck, means for closing the neck against the escape of gas, and stop means borne by that portion of the cord extending beyond the neck to prevent the cord from being drawn upwardly into the body of the balloon.

2. A meteorological balloon including expansible envelope portions and neck portions, a plug of elastic material having an aperture the walls of which are adapted to engage a suspension cord passed through said aperture, the degree of engagement of the plug with the cord being sufficient to prevent substantially the escape of lifting gas within the balloon envelope, but insufilcient to prevent the sliding of the plug along the suspension cord as the balloon expands.

3. A follower balloon adapted for tandem balloon flights comprising an expansible, substantially spherical envelope, a neck located at the South pole of said envelope, a resilient plug attached to said envelope at the North pole thereof, said plug being provided with a pierced aperture, a cord extending through the balloon outwardly through said neck and upwardly through said plug and maintained in substantially gastight but sliding engagement with the walls of said aperture, and means to prevent movement of the cord relative to the neck of said balloon.

4. The method of flying balloons in tandem flight and preventing contact of the balloon envelopes with each other or with the suspension cord which consists in passing the suspension cord diametrically through the follower balloon, afixing the suspension cord to the lowermost portion of the follower balloon and also to the lead balloon and allowing the envelope to slide upwardly along the cord as the follower balloon expands to maintain the follower balloon axially aligned with the lead balloon.

DOMINA C. JALBERT.

No references cited. 

